Device and method for carrying out a cryptographic method

Abstract

A device for carrying out a cryptographic method includes: a cryptographic unit carrying out at least one step of the cryptographic method; and a functional unit carrying out a deterministic function as a function of input data supplied to the device and at least one secret key.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a device and a method for carrying out a cryptographic process.[0003]2. Description of the Related Art[0004]Such devices and methods are known, for example from U.S. Pat. No. 7,599,488 B2.[0005]The known device has a microprocessor core to which a random number generator is allocated in order to manipulate the execution of cryptographic instructions on the microprocessor core in a random manner. This makes cryptographic attacks on the microprocessor core carrying out the cryptographic method more difficult. In particular, so-called differential power analysis (DPA) attacks are made more difficult, because the temporal relationship between a regular clock signal and the actual execution of the individual steps of the cryptographic method by the microprocessor core is concealed using the random numbers.[0006]A disadvantage of the known system is the fact that a random number generator is r...

AI Technical Summary

Benefits of technology

[0010]A further advantage of the present invention is that complex random generators and the like can be done without, because the functional unit according to the present invention uses a deterministic function and at least one secret key for it.

[0011]In an advantageous specific embodiment, it is provided that the cryptographic unit and the functional unit are each implemented as an integrated circuit, preferably in the same integrated circuit (IC), so that the advantageously achieved concealing of the electromagnetic radiation, energy signatures, etc., of the cryptographic unit is achieved to a particularly high degree. Through suitable selection of the circuit layout, further improvements in this regard can be achieved, for example by spatially integrating individual functional components of the functional unit in component regions of the cryptographic unit, and vice versa.

[0012]In a further advantageous specific embodiment, it is provided that the cryptographic unit and the functional unit have a common terminal for an electrical power supply, i.e. can be fed from the same energy source. In this way, the energy (consumption) signatures of the two units are superposed, which also makes DPA attacks more difficult.

[0013]In order to realize the advantages named above, it is not necessary to functionally use computing results or other quantities processed by the functional unit in the cryptographic unit. Rather, a “parallel operation,” in which both units (cryptographic unit and functional unit) operate also independently of one another and, at least at times, temporally overlapping one another

Problems solved by technology

This makes a precise analysis of the cryptographic unit more difficult.

Given a suitable length of the secret key, for example also 128 bits or more,

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